SCM-198 inhibits microglial overactivation and attenuates A?(1-40)-induced cognitive impairments in rats via JNK and NF-?B pathways.
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ABSTRACT: BACKGROUND: Neuroinflammation mediated by overactivated microglia plays a key role in many neurodegenerative diseases, including Alzheimer's disease (AD). In this study, we investigated for the first time the anti-neuroinflammatory effects and possible mechanisms of SCM-198 (an alkaloid extracted from Herbaleonuri), which was previously found highly cardioprotective, both in vitro and in vivo. METHODS: For in vitro experiments, lipopolysaccharide (LPS) or ?-amyloid(1-40) (A?(1-40)) was applied to induce microglial overactivation. Proinflammatory mediators were measured and activations of NF-?B and mitogen-activated protein kinases' (MAPKs) pathways were investigated. Further protective effect of SCM-198 was evaluated in microglia-neuron co-culture assay and Sprague-Dawley (SD) rats intrahippocampally-injected with A?(1-40). RESULTS: SCM-198 reduced expressions of nitric oxide (NO), TNF-?, IL-1? and IL-6 possibly via, at least partially, inhibiting c-Jun N-terminal kinase (JNK) and NF-?B signaling pathways in microglia. Co-culture assay showed that activated microglia pretreated with SCM-198 led to less neuron loss and decreased phosphorylation of tau and extracellular signal-regulated kinase (ERK) in neurons. Besides, SCM-198 also directly protected against A?(1-40)-induced neuronal death and lactate dehydrogenase (LDH) release in primary cortical neurons. For in vivo studies, SCM-198 significantly enhanced cognitive performances of rats 12 days after intrahippocampal injections of aged A?(1-40) peptides in the Morris water maze (MWM), accompanied by less hippocampal microglial activation, decreased synaptophysin loss and phosphorylation of ERK and tau. Co-administration of donepezil and SCM-198 resulted in a slight cognitive improvement in SD rats 50 days after intrahippocampal injections of aged A?(1-40) peptides as compared to only donepezil or SCM-198 treated group. CONCLUSIONS: Our findings are the first to report that SCM-198 has considerable anti-neuroinflammatory effects on inhibiting microglial overactivation and might become a new potential drug candidate for AD therapy in the future.
SUBMITTER: Hong ZY
PROVIDER: S-EPMC4156960 | biostudies-literature | 2014
REPOSITORIES: biostudies-literature
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